A number of gasification processes in existence or being developed, e.g., gasification of coke, residues, coal, etc., produce synthesis gases having various quantities of H.sub.2, CO, CO.sub.2 and H.sub.2 S, as well as minor "impurity" components of NH.sub.3 and HCN. In the case of synthesis gases derived from the gasification of coal, for example, the ratio of CO to H.sub.2 may range from 0.9 to 12:1, and the gas may contain from 0.05 percent to 10 percent by volume of H.sub.2 S. If the "syn-gas" is to be used for fuel purposes, the ratios mentioned are generally satisfactory, and little need be done except elimination of contaminants such as H.sub.2 S and HCN.
On the other hand, if other uses for the synthesis gas are contemplated, such as hydrogen production or use as a feedstock for synthesis operations, the ratio of H.sub.2 to CO may become critical, and adjustment of the H.sub.2 /CO ratio to the right range may require great expense. Accordingly, a process that provided a ready method of adjustment of the H.sub.2 /CO ratio from such gases, even to the production of hydrogen alone, could have great economic importance. The invention relates to such a process.